Combination drum and belt sanding surfacing machines



March 17, 1964 J NYLUND ETAL 3,124,909

COMBINATION DRUM AND BELT'SANDING SURFACING MACHINES Filed April 24,1961 John AZNyJund Frank clMiehe INVENTORS United States Patent3,124,909 COMBENATION DRUM AND BELT SANDING SURFACING MAC John A.Nylund, Portland, and Frank J. Miehe, Lake Grove, 0reg., assignors toTidland Machine Company, a corporation of Washington Filed Apr. 24,1961, Ser. No. 105,184 18 Claims. (Cl. 51-141) This invention relates tosanding machines or sanders. The particular embodiment of the inventiondisclosed herein has utility in sanding the faces of panels or lumber.The sanding machine may be used to smooth a panel in a limited cuttingtype of operation, and also may be used in sizing or dimensioning apanel so that when it leaves the sander it has uniform thickness.

A general object of the invention is to provide improved sandingmechanism that may be used with equal facility in either a limitedcutting or a dimensioning type of sanding operation, or in sandingoperations somewhere between these types.

Another object is to provide a sander that can perform both limitedcutting and dimensioning type of sanding operations, and is quickly andeasily converted from one type of operation to the other.

A still further object is to provide an improved sander capable of firstsanding and then polishing an article, which utilizes a sanding belt andresilient pressure-producing mechanism acting on the belt for performingthe polishing action.

Another object of the invention is to provide an improved constructionfor such a resilient pressure-producing mechanism in a sander that isoperable to produce regular and uniform pressures in those portions of asanding belt performing a polishing action, without excessive unequaldistortions occurring in the resilient part of the mechanism. Themechanism also features means whereby heat as the result of friction inthe mechanism is quickly dissipated. The pressure-producing mechanism inthe sander can be operated over long periods without replacement neededin the parts thereof.

Other objects and advantages of the invention will become more fullyapparent upon reading the following description. In the description ofthe invention that follows, reference is made to the accompanyingdrawings, wherein:

FIG. 1 is a side elevation of a sanding machine as contemplatedaccording to one embodiment of this invention;

PEG. 2 is an end view, on a somewhat enlarged scale, of portions ofresilient pressure-producing mechanism present in the sander used inpressing a sanding belt against an article such as a panel during thefinal polishing and smoothing of the article;

FIG. 3 is a perspective view of table structure present in the sanderprovided for supporting the underside of an article as its top side issanded;

FIG. 4 is a perspective View illustrating a removable insert used toprovide rigidity in the table structure of FIG. 3; and

FIG. 5 illustrates another removable insert in the sander.

Common types of sanding operations performed on articles such as plywoodpanels, for instance, are size or dimension sanding of a panel, where apanel of uniform thickness is produced regardless of irregularities inthickness prior to sanding, and limited cutting where smoothnessprimarily is desired without regard to irregularities in thickness. Theformer type of sanding might be used with plywood having relativelythick outer veneer layers, whereas the latter type might be carried outon a panel which has a very thin specialty wood veneer over 3,124,909Patented Mar. 17, 1964 its faces, where excessive sanding would destroythe veneer layers. Some panels, of course, require sanding treatmentssomewhere between the two types of sanding just discussed. An importantadvantage and feature of the invention is that the sander may readily beset up for either type of sanding, or for any kind of sanding betweenthe two extremes just outlined. Adjustment is made with a minimum amountof shut-down time, and by means readily understood by an ordinary millworker.

In the sanding of a panel, whether limited cutting or dimensioning isbeing done, it is desirable that a sander be provided with means forfast cutting (to remove most of the wood), and also with means forsmoothing and finally polishing the panel. A simple constructionproviding for both fast cutting and smoothing comprises a sanding drumor pulley that trains a sanding belt, with means for supporting a panelagainst the belt where it extends over the sanding drum so that theseportions of the belt can perform fast cutting, and to the off-bearingside of this sanding drum resilient pressure-producing means acting on arun of the belt extending from the drum. Such pressure-producing meansurges the belt run against an article with lighter pressure than thedrum, so that a polishing action results. Important in obtaining goodpolishing is that the pressure-producing means impart even pressures tothe belt run across its entire width, so that a panel passing againstthe belt run have even polishing pressure applied thereto. Pressuresshould also stay fairly uniform irrespective of thickness variations inthe panel. This invention features a pressure shoe for thepressure-producing means which takes care of the above outlinedrequirements in a highly satisfactory manner.

Referring now to the drawings, the sanding machine or sander isindicated in FIG. 1 generally at 10. The sander comprises a frame 12supporting the operating parts of the sander off the ground. Mounted onframe 12 is a conveyer mechanism generally indicated at 14 fortransporting articles such as panels in a path through the sander, andsanding mechanism 16 for removing wood from the panel as the same istransported by mechanism 14.

Conveyer mechanism 14 comprises, at the feed end of the sander (or theright end in FIG. 1), a pair of opposed pinch rolls 18, 20. One of these(in the drawings, the upper roll 18) has a rubber covering 19, whichincreases the grab of the pinch rolls, and accommodates variations inthickness in a panel passed between the rolls. The pinch rolls aresuitably journaled in bearings such as bearings 22 secured to the frame.

At the off-bearing or discharge end of the sander are another pair ofpinch rolls 24, 26, similar to rolls 13, 20, and these are journaled inbearings 28. Roll 24 is provided with a rubber covering 25.

A panel, illustrated by panel 30, is transported by pinch rolls 18, 20and 24, 26 in a substantially horizontal path through the sander, withmovement of the panel being from right to left. The pinch rolls aredriven in any suitable manner, as by motor 32 connected to the upperpinch roll of each set by drive belt 34, 36.

Panel 30 while traveling through the sander has its bottom face slidablysupported on a flat table or guide 40 extending beneath sandingmechanism 16. Sliding against the top face of the panel, i.e., the facethat is subjected to sanding, is a guide 4-2 on the feed side of sandingmechanism 16, and a guide 44 on the off-bearing side of mechanism 16.

Describing now sanding mechanism 16, this comprises a sanding belt 50trained over pulleys or drums indicated at 52, 54, 56. Drum 52constitutes a driving drum, and

3 druilns 54, 56 constitute sanding and idler drums, respective y.

Driving drum 52 is supported on the top of frame 10 in bearings such asbearing 64). The driving drum is rotated under power. Thus, connected tothe drum to drive it is a motor 62. In operation of the sander, the drumis rotated by motor 62 in a counterclockwise direction in FIG. 1, andsanding belt 50 travels in the direction indicated by the arrow in FIG.1.

Sanding drum 54 is journaled on the frame in bearings such as bearing64. The drum is positioned in the embodiment illustrated approximatelydirectly below the driving drum, and opposite and a short distance abovethe top of table or guide 40. Belt 50 on traveling about the sandingdrum produces the principal cutting of a panel during operation of thesander. The spacing between the top of table or guide 40 and the outersurface of the belt at the base of the sanding drum determines thethickness of a sanded panel.

Idler drum 56 is journaled on frame 10 in bearings such as hearing 66. Arun 5001 of sanding belt 50 extends from the sanding drum toward theidler drum. Training this belt run and slidably pressing against theinner surface of the belt run is pressure-producing mechanism 68.Pressure-producing mechanism 68 by forcing portions of run 50aresiliently downwardly against the top of a panel after cutting of thepanel by the sanding drum polishes the panel and thus finishes it off.In the embodiment of the invention illustrated, mechanism 68 comprises asupport 70 fixed to the frame, and secured to support 70 a bracket 72.Bracket 72 is provided at the base thereof with a removable shoeconstruction 74 extending across the frame the width of belt 51), and itis the removable shoe construction that contacts the inner surface ofthe sanding belt as it travels past mechanism 68.

With reference now more particularly to FIG. 2, shoe construction '74comprises a metal mounting plate 76 as long as the belt 50 is wide, withopposed edges 77, 78 turned toward each other on one side of the plateto define grip flanges for the plate. On the other side of the platebetween opposed edges 77, 78 are an expansive heel portion 80, and arecessed portion 82 next to heel portion 80. Within recessed portion 82,and with an outer surface substantially flush with and forming a smoothcontinuation of the outer surface of heel portion 8%) is a resilient pad84. This may be made of rubber, a synthetic, and the like.

Pad 84 is held in position within the recessed portion by anantifriction covering 86 (that may be, for instance, a graphite coatedcanvas sheet, or similar low coeflicient of friction material). Covering86 has edges 87, 88 that extend over edges 77, 78 of the mounting plate.Between covering 86 and the outer surface of heel portion and the outersurface of resilient pad 84 is a thin, metallic (and thereforeconducting) sheet 90. The sheet extends over the heel portion and thenceover shoulder 78 beneath edge 38, and is in intimate contact with theheel portion.

Covering 86 and metal sheet 90 along edge 78 of the plate are secured inplace on the mounting plate by an elongated clip 96. A similar clip 98secures edge 87 of the covering to edge 77 of the plate. The clips havea length coextensive with the length of the metal mounting plate. Withthe shoe construction 74 mounted on bracket 72, plate edge '78 and clip96 about it fit within groove 99 along one side of bracket 72. Plateedge 77 and clip 98 fit over the end of the bracket, as illustrated inFIG. 2.

Directly behind heel portion 80 of the mounting plate is a pipe orconduit 102 lying within an elongated groove 104 provided bracket 72.The conduit extends the length of the shoe construction, and means (notshown) is provided for circulating a coolant through the conduit. Theconduit has a surface that contacts the metal mounting plate. Duringoperation of the sander, a coolant such as water and the like iscirculated through the conduit, with such coolant carrying heat awayfrom the heel portion. Belt 50 slides on the shoe construction, and heatof friction so developed is conducted through metal sheet and the metalheel portion to conduit 102.

It will be noted with reference to FIG. 1 that run 50a of the sandingbelt between drums 54, 56 bows outwardly with respect to a plane tangentto the two drums or pulleys. Such a tangent plane is indicated by thedashed line 107. This is because the shoe construction is positionedbelow such a tangent plane, and belt 50 that slides over the shoeconstruction, in doing so, travels below the plane. Bowing of the belttensions the belt, so that it slides tightly over the shoe constructionwith friction between the shoe construction and belt tending to produceheat.

A feature of the invention is the provision of a heel portion 80 whichis conductive (plate 76 is metallic), and which performs substantiallyall tensioning of the belt between drums 52, 56. Note that it is theheel portion that protrudes the greatest distance from tangent plane107. The heel portion thus constitutes a deflecting portion in the shoeconstruction, such deflecting portion in addition to being heatconductive being nonyieldable. Pad 84 adjacent the deflecting portionprimarily functions as a resilient backing for belt run Sila betweendrum 54 and the heel portion, the belt run progressing in substantiallya straight line along this portion thereof. As a consequence, while pad84 is effective yieldably to press the sanding belt against a panel toproduce a polishing action, excessive distortions in the pad tend to beminimized, and heat build up therein also is minimized. The constructionmakes for a longer pad life, and also produces a more even polishingaction.

Considering now the construction of table or guide 40, this comprises aplate 109 substantially rectangular in plan, supported at each of itsfour corners by a threaded stud 110 that is aflixed to the plate andthat extends through a platform 112 which is integral with the frame.Threaded adjusting sprockets 114 screwed onto studs 110 are journaled inplatform 112. Turning of the adjusting sprockets functions to raise orlower the threaded studs relative to platform 112. The adjustingsprockets are turned in unison by means of a crank handle 116 having asprocket 118' secured thereto that engages a chain 121), such chainbeing trained over adjusting sprockets 114. The studs, adjustingsprockets, handle 116 and associated mechanism are used to positionproperly the top of table 40 relative to the base of drum 54.

Plate 109 has upstanding shoulders 126, 128 extending along its frontand rear edges. Fitted between these shoulders is an envelope structure,indicated generally at 130 and shown separated from the sander in FIG.3.

Envelope structure 130 comprises a flat, bottom piece 134 that isrectangular in shape. Extending along the forward and rear edges of thepiece and affixed to the piece are strips 136, 138, respectively. These,for instance, may be made of rubber, or suitable flexible and resilientsynthetic material. Over the top sides of the strips 136, 138 there isaflixed a rectangular, flexible top piece 140. This has an upper surfacethat is smooth, selected so that a low coefflcient of friction existsbetween the top of the piece and a panel when the panel slidesthereover. Suitable smoothness and flexibility are found in plasticsheets, although relatively thin, smoothed metal sheets may also beused.

Top piece 140 and bottom piece 134 together with the flexible strips136, 138 together define a cavity 141 within the envelope structure. Thecavity receives an insert, such as that illustrated in perspective inFIG. 4 and indicated at 142. The insert is used to provide support forthe flexible top piece and the resilient strips underlying it along itsedges, whereby a panel passed over the envelope structure will be pushedupwardly with suitable pressure against the base of the sanding drum andpressure-producing mechanism 68.

Insert 142 is shaped snugly to be received within cavity 141. In somesanding operations, the insert may be made of stiff, nonyieldablematerial, such as a solid piece of plastic or wood. In such an event,the top surface of piece 140 is rigid and unyielding, and table 40supports a panel at a fixed distance from the sanding drum. In othersanding operations, a resilient pad may be used, made of rubber orsynthetic. With such an insert, top piece 140 is permitted to give, andthe function of the table 40 is more to press a panel with a uniformpressure against the sanding drum. Inserts between these extremes mayalso be used.

Guide 44 to the off-bearing side of the sanding drum comprises anexpansive plate 150, made of steel or other rigid material, extendingacross the path of travel for panels. The plate is aflixed to a support152 joined in a fixed position on frame 12.

Considering now guide 42, this is somewhat similar to table or guide 40in construction. The guide comprises a heavy plate 156 extending acrossthe path of a panel through the sander and secured to frame 12 of thesander in a suitable manner. Fastened to the underside of plate 156 arespaced-apart flexible strips 158, 160 similar to strips 136, 138. Joinedto the bottom sides of the strips is a flexible bottom piece 164. Bottompiece 164, like piece 146 of table 40, is smooth-surfaced, and made of amaterial having a low coefiicient of friction when a panel slidesthereacross. A plastic sheet is also preferable for this bottom piece.

Plate 156, bottom piece 164, and strips 158, 160 constitute envelopestructure defining a cavity 166 within the envelope structure. Thiscavity receives a removable insert, such as the insert 168 illustratedin FIG. 5. The insert fits snugly within the cavity and provides supportfor flexible piece 164. For some purposes, an insert which is flexibleand resilient may be used, whereas in other sanding operations a rigid,stiff insert is preferred. With a stiff insert, the position of thebottom of piece 164 is fixed, whereas with a flexible insert, the bottommay yield with variations in panel thickness.

Explaining now how the sander of the invention may be used, first of allit will be assumed it is desired to size or dimension a panel, so thatthe finished panel has uniform thickness regardless of nonuniformityprior to sanding. For such sizing or dimensioning, the operator placeswithin cavity 141 of'table 40 a rigid noncompressible insert. This backsup top piece 140 so that the upper surface thereof occupies a fixedplane, which is located a predetermined distance from the bottom of thesanding belt as it passes over the sanding drum. For cavity 166 of guide42, an insert of resilient, yieldable material is selected. When a panelis then passed through the sander, guide 42 functions to hold the panelin place, but gives to take care of variations in thickness. Since therelative positions of the top of table 40 and the sanding drum arefixed, the panel passes beyond the drum only on reaching desiredthickness.

In a limited cutting type of sanding operation, where smoothness isdesired over true thickness, cavity 166 of guide 42 is filled with arigid insert, whereby the top of a panel is guided to the sanding drumwhile supported at a fixed elevation relative to the drum. On the otherhand, cavity 141 of table 40 is filled with a yieldable, compressibleinsert, that enables top piece 140 to give with respect to the sandingdrum. When a panel now is fed the sander, the resilient nature of theinsert for table 40 functions to enable thick and thin areas of thepanel to be pressed against the sanding drum with approximately uniformpressure.

Using the sanding machine, panels that have patches and localized areasof unevenness are handled efficiently and effectively. Where a resilientinsert is used, resiliency extends both transversely of and in adireciton parallel to the path of travel for a panel.

Particularly important, a Workman may change the type of sandingoperation with a minimum of shut down 6 time. The two extreme types ofsanding may be performed, as well as sanding operations lying somewhatin between. Once the type of sanding has been determined, it is an easymatter to insert proper inserts into suitable cavities.

While a modification of the invention has been described, it is apparentthat other embodiments and variations are possible without departingfrom inventive concepts present in the invention. It is desired not tobe limited to the specific embodiment of the invention disclosed, but tocover all modifications and variations that would be apparent to oneskilled in the art, and that come within the scope of the appendedclaims.

It is claimed and desired to secure by Letters Patent:

1. In a sanding machine having a pair of spaced pulleys and a sandingbelt traveling over the pulleys with a run of the belt extending betweenthe pulleys, pressure means intermediate the pulleys training said runof the belt, said pressure means comprising a deflecting portiondeflecting said run of the belt outwardly from a plane tangent to thetwo pulleys and tensioning the belt, said deflecting portion being ofnonyieldable material that is heat conductive, means for cooling saiddeflecting portion including conduit means for circulating a coolant,and a backing portion of resilient material yieldably backing a portionof said belt between said deflecting portion and one of said pulleys.

2. In a sanding machine having a pair of spaced pulleys and a sandingbelt traveling over the pulleys with a run of the belt extending betweenthe pulleys, pressure means intermediate the pulleys training said runof the belt, said pressure means comprising a deflecting portiondeflecting said run of the belt outwardly from a plane tangent to thetwo pulleys and tensioning the belt, said deflecting portion being ofnonyieldable material that is heat conductive, a backing portion ofresilient material yieldably backing a portion of said run of the beltbetween said deflecting portion and one of said pulleys, a lowcoeflicient of friction cover extending over said deflecting and backingportions having an outer surface contacting said belt with said runsliding thereagainst, and a heatconducting sheet between said cover andsaid backing and deflecting portions and in contact with said deflectingportion whereby heat may be conducted from the sheet to said deflectingportion.

3. In a sanding machine having a pair of spaced pulleys and a sandingbelt traveling over the pulleys with a run of the belt extending betweenthe pulleys, pressure means intermediate the pulleys training said runof the belt, said pressure means comprising an expansive andsmooth-surfaced deflecting portion over which the belt slides, saiddeflecting portion deflecting the belt outwardly from a plane tangent tothe two pulleys and tensioning the belt and being made of nonyieldablematerial that is heat conductive, means for cooling said deflectingportion including conduit means for circulating a coolant, and a backingportion adjacent said deflecting portion of resilient material andyieldably backing a portion of the belt between said deflecting portionand one of said pulleys, said run of the belt extending in substantiallya straight line from said deflecting portion over said backing portionto said one pulley.

4. In a sanding machine having a pair of spaced pulleys and a sandingbelt traveling over the pulleys with a run of the belt extending betweenthe pulleys, pressure means intermediate the pulleys training said runof the belt, said pressure means comprising an expansive andsmooth-surfaced deflecting portion over which the belt slides, saiddeflecting portion deflecting the belt outwardly from a plane tangent tothe two pulleys and tensioning the belt and being made of nonyieldablematerial that is heat conductive, a backing portion adjacent saiddeflecting portion of resilient material and yieldably backing a portionof the belt between said deflecting portion and one of the pulleys, saidrun of the belt extending in substantially a straight line from saiddeflecting portion over said backing portion to said one pulley, a lowcoeflicient of friction cover extending over said deflecting and backingportions having an outer surface contacting said belt with said runsliding thereagainst, and a heat-conducting sheet between said cover andsaid backing and deflecting portions and in contact with said deflectingportion whereby heat may be conducted from the sheet to said deflectingportion.

5. In a sanding machine having a pulley and a sanding belt trained oversaid pulley and means for guiding material against said belt where itextends about said pulley, pressure-producing mechanism on theoffbearing side of said pulley constructed slidably to support the beltand hold it against material being sanded, said pressureproducingmechanism comprising a metal mounting plate having opposed edges turnedtoward each other on one side of the plate to define grip flangestherefor, said mounting plate between said opposed edges presenting onthe other side of said plate an expansive heel portion extending thewidth of the belt and adjacent said heel portion and toward said pulleyfrom said heel portion a recessed portion also extending the width ofthe belt, a resilient cushion disposed within said recessed portion andbounded by an outer surface that forms a smooth continuation of thesurface of said heel portion, and a low coefiicient of friction coverextending over the surface of said heel portion and said outer surfaceof said cushion.

6. In a sanding machine having a sanding belt, pressure-producingmechanism constructed slidably to support the belt and hold it againstmaterial being sanded, said pressure-producing mechanism comprising ametal mounting plate having opposed edges turned toward each other onone side of the plate to define grip flanges therefor, said mountingplate between said opposed edges presenting on the other side of saidplate an expansive heel portion extending the width of the belt andadjacent the heel portion along the length of the belt a recessedportion also extending the width of the belt, a resilient cushiondisposed within said recessed portion and bounded by an outer surfacethat forms a smooth continuation of the surface of said heel portion, alow coefficient of friction cover extending over the surface of saidheel portion and said outer surface of said cushion, and aheat-conducting sheet between said cover and said outer surface of saidcushion and said surface of said heel portion contacting said heelportion whereby heat may be conducted from the sheet to the heelportion.

7. In a sanding machine having a sanding belt, pressure-producingmechanism constructed slidably to support the belt and hold it againstmaterial being sanded, said pressure-producing mechanism comprising ametal mounting plate having opposed edges turned toward each other onone side of the plate to define grip flanges therefor, a bracketmounting said mounting plate with said grip flanges detachably holdingthe plate on said bracket, coolant conduit means for circulating acoolant mounted on the bracket and in contact with said metal mountingplate, said mounting plate between said opposed edges presenting on theside opposite said one side an expansive heel portion extending thewidth of the belt and adjacent the heel portion along the length of thebelt a recessed portion also extending the width of the belt, aresilient cushion disposed within said recessed portion and bounded byan outer surface that forms a smooth continuation of the surface of saidheel portion, a low coefiicient of friction cover extending over thesurface of said heel portion and said outer surface of said cushion, anda heatconducting sheet between said cover and said outer surface of saidcushion and said surface of said heel portion contacting said heelportion whereby heat may be conducted from the sheet to the heelportion.

8. In a sanding machine, a frame, a pair of spaced pulleys mounted onthe frame, a sanding belt traveling over the pulleys, means fortransporting work in a path adjacent one of said pulleys, guide means tothe feed side of said one pulley constructed to guide work while ittravels toward said one pulley by sliding against the side of the workthat is to be sanded, guide means disposed opposite said one pulleyconstructed to guide work during the actual sanding thereof by slidingagainst the other side of the work, each of said guide means comprisingenvelope structure with a yieldable surface facing said path that slidesagainst the work, and a removable insert Within each envelope structureproviding support for said surface.

9. in a sanding machine for panels having a frame and sanding mechanismfor sanding a side of a panel as it travels through the sander, a firstguide means disposed to the feed side of said sanding mechanismconstructed to guide a panel while it travels toward said sandingmechanism by sliding against the side of the panel that is to be sanded,a second guide means disposed opposite said sanding mechanismconstructed to guide a panel during the actual sanding thereof bysliding against the other side of the panel, at least one of said guidemeans providing yieldable support for a panel to be sanded, said one ofsaid guide means having a removable insert determining the yieldabilityof said one of said guide means and the yieldability of the support thatthe guide means provides a panel as the panel slides thereagainst.

10. In a sanding machine for panels, a table with an expansive andsmooth surface for slidably supporting one side of a panel as the sideopposite is sanded and defining a path of travel for the panel, saidsurface being yieldable in a direction normal to said path, a pair ofguides spaced along said path of travel disposed opposite said table,each of said guides being constructed to slide against said oppositeside of said panel, sanding mechanism intermediate the guides andopposite said table for sanding said opposite sides, the guide means tothe feed side of said sanding mechanism including a yieldable surfacethat supports said opposite side of said panel, said table and saidguide to the feed side of said sanding mechanism each having a removableinsert that determines the yieldability of its said surface and theamount it may yield as a panel slides thercagainst.

11. in a sanding machine for panels, a frame, a table mounted on theframe with an expansive and smooth surface for slidably supporting oneside of a panel as the side opposite is sanded and defining a path oftravel for the panel, a pair of guides mounted on the frame spaced alongsaid path of travel and disposed opposite said table, each of saidguides being constructed to slide against said opposite side of thepanel, a sanding belt and a pair of pulleys mounted on the frame withthe pulleys training the belt and with the belt where it extends aboutone pulley adjacent said path and in position to contact said oppositeside of the panel at a location disposed between said guides, andpressure mechanism bearing on the inside of a run of said sanding beltas it extends between the pulleys, said pressure mechanism being to theoffbearing side of said one pulley and producing contact of said beltwith a panel, said pressure mechanism comprising a deflecting portiondeflecting said run of the belt between the pulleys outwardly from aplane tangent to the two pulleys whereby tension is produced in thebelt, said deflecting portion being of nonyieldable material that isheat conductive, said pressure mechanism also having a backing portionof resilient material yieldably backing a portion of said run of thebelt between said deflecting portion and said one pulley, said run ofthe belt extending in substantially a straight line from said deflectingportion to said one pulley, the guide to the feed side of said onepulley and said table each having a removable insert determining itsresiliency and the amount that it may yield as a panel slidesthereagainst.

12. The apparatus of claim 11, wherein the table and the guide to thefeed side of said one pulley each comprises envelope structure with aflexible and substantially flat side facing the path of travel for apanel, the removable insert being positioned within the envelopestructure and providing support for the side.

13. In a sanding machine, a frame, a rotatable sanding drum mounted onsaid frame, a sanding belt trained over said drum, guide means disposedopposite said beit where it is trained over said drum constructed toguide work against said belt where it is trained over said drum duringthe actual sanding of the work, said guide means comprising envelopestructure with a yieldable surface facing said drum, and a removableinsert within said envelope structure providing support for saidsurface.

14. In a sanding machine, a continuous movable sanding belt, meanstraining the sanding belt including a drum mounted with the sanding beltextending about a portion of the periphery of said drum, resilient meansmounted opposite said belt where it extends about a portion of theperiphery of said drum yieldable away from said belt, and meansproviding a surface for supporting work as it is sanded extending oversaid resilient means and interposed between said resilient means andsaid belt where it extends about a portion of the periphery of saiddrum.

15. In a sanding machine, a continuous movable sanding belt, meanstraining the sanding belt including a drum mounted with the sanding beltextending about a portion of the periphery of said drum, resilient meansmounted opposite said belt where it extends about a portion of theperiphery of said drum yieldable away from said belt, and meansproviding a surface for supporting work as it is sanded extending oversaid resilient means and interposed between said resilient means andsaid belt where it extends about a portion of the periphery of saiddrum, said means providing a surface for supporting work having apredetermined minimum spacing from said belt where it is trained oversaid drum and being yieldable away from said belt and drum together withsaid resilient means on the passage of work of greater thickness thansaid minimum spacing thereover and against said belt.

16. The sanding machine of claim 15, wherein the means providing asurface for supporting work and said resilient means comprises envelopestructure with a surface facing the drum for supporting work, and aremovable insert within said envelope structure.

17. In a sanding machine, a continuous movable sanding belt, meanstraining the sanding belt including a drum mounted with the sanding beltextending about a portion of the periphery of said drum, means defininga path of travel for work positioned opposite said belt where it extendsabout a portion of said drum and spaced from said drum a predetermineddistance, and resilient means supporting said means defining a path oftravel for work, said last-mentioned means and the means defining thepath for travel for work being yieldable away from said belt where itpasses over said portion of said drum.

18. In a sanding machine, a pair of spaced pulleys mounted for rotationabout parallel axes, a sanding belt trained over the pulleys with a runof the belt extending between the pulleys, pressure means intermediatethe axes of said pulleys and to one side of the plane defined by saidaxes over which said belt run travels, said pressure means beingoperable to deflect said belt run outwardly from a plane tangent to thetwo pulleys and to support said belt run in a position where the beltrun, starting at each pulley and progressing toward the other pulley,defines an acute angle relative to said plane tangent to the twopulleys, said pressure means comprising a deflecting portion thatengages said run of the belt at that point where the belt run is spacedits greatest distance from said plane tangent to the two pulleys, saiddeflecting portion being of non-yieldable material and heat conductive,said pressure further comprising a backing portion of resilient materialyieldably backing a portion of said run of the belt between saiddeflecting portion and one of said pulleys, and means for guiding workin a path first adjacent said belt where it travels over said one pulleyand then over said belt where it travels over said backing portion.

References Cited in the file of this patent UNITED STATES PATENTS1,921,513 Emmons Aug. 8, 1933 2,761,256 OConnor Sept. 4, 1956 2,762,173Bottcher Sept. 11, 1956 2,791,070 Schaller May 7, 1957 2,895,262 Nylundet al. July 21, 1959 2,934,863 Pendergast May 3, 1960

1. IN A SANDING MACHINE HAVING A PAIR OF SPACED PULLEYS AND A SANDINGBELT TRAVELING OVER THE PULLEYS WITH A RUN OF THE BELT EXTENDING BETWEENTHE PULLEYS, PRESSURE MEANS INTERMEDIATE THE PULLEYS TRAINING SAID RUNOF THE BELT, SAID PRESSURE MEANS COMPRISING A DEFLECTING PORTIONDEFLECTING SAID RUN OF THE BELT OUTWARDLY FROM A PLANE TANGENT TO THETWO PULLEYS AND TENSIONING THE BELT, SAID DEFLECTING PORTION BEING OFNONYIELDABLE MATERIAL THAT IS HEAT CONDUCTIVE, MEANS FOR COOLING SAIDDEFLECTING PORTION INCLUDING CONDUIT MEANS FOR CIRCULATING A COOLANT,AND A BACKING PORTION OF RESILIENT MATERIAL YIELDABLY BACKING A PORTIONOF SAID BELT BETWEEN SAID DEFLECTING PORTION AND ONE OF SAID PULLEYS.